The primary function of the skin is to protect the body against environmental stresses and to prevent against dehydration.
TEWL is a term used in dermatology to characterize the loss of water that passes from the inside of a body through the epidermal layer (skin) to the surrounding atmosphere via diffusion and evaporation processes.
TWEL is also the most physiological readout to assess compromised skin barrier function as it is well established that an impaired skin barrier eventually leads to loss of water throughout the skin.
Transepidermal water loss can have genetic and/or an allergic etiology.
Genetic components are involved in the water loss observed in chronological aging, atopic dermatitis, reactive skin, dry skin, atopic diathesis in rosacea and perioral dermatitis.
Allergic diseases leading to water loss include atopic dermatitis, eczema, dry skin.
In TEWL disorders, the normal water loss rate is increased due to a diminished barrier function of the epidermis. A TEWL disorder is thus characterized by the symptoms of a dehydrated epidermis like dry or scaly skin. TEWL disorders in humans are often caused or associated with atopic dermatitis (also called eczema) and reactive skin. Other diseases with skin inflammatory condition are also associated with an increased TEWL such as injury, infection and/or severe damage as in the case of burns psoriasis, and a range of inflammatory skin conditions such as atopic diathesis in rosacea and perioral dermatitis).
TEWL having a genetic component can lead to dry skin or reactive skin and TEWL having allergic component can lead to atopic dermatitis.
For the establishment of atopic dermatitis and reactive skin a genetic disposition (polymorphism genes such as in filaggrin gene or SPINK5) and an irritant like an allergen are usually required. Subjects suffering from atopic dermatitis show reactions of the skin against agents that usually do not cause any skin irritation in healthy subjects (like soap, cold, transpiration, stress).
In relation to skin barrier function, a genetic barrier function disease can lead to chronological aging, psoriasis or non allergic eczema. Allergic component of skin barrier function disease can lead to sensitive skin. Measurement of TEWL is thus a way to measure loss of water through the epidermal layer (skin) but also the skin barrier function through its TEWL component.
Previous treatments usually aimed at applying moistening skin gels or compositions comprising a variety of artificial or natural ingredients directly to the skin to treat the symptoms of TEWL (see WO 2003090670 A2).
Alternatively, a variety of nutritional supplements have been suggested (see U.S. Pat. No. 7,297,677 B2) but those did not include plant phenols. Alternative approaches aimed at avoiding those agents that caused the reaction of the skin in the environment or the diet.
It was therefore the object of the invention to provide a novel composition for the treatment of a TEWL disorder and/or to increase skin barrier function. Preferentially, this composition can also be orally administered.